For the purpose of research or for practical use, the prior art has proposed keeping neurons in culture medium (particularly liquid medium) to construct neuron networks in vitro, with the neurons in a live state.
In NPL 1, for example, there is described formation of a region surrounded by a plurality of protrusions on a Si plate bearing a transistor, as shown in FIG. 2, placement of a large ganglion, as an aggregate of peripheral neurons, of L. stagnalis, therein and detection of variations in the potential of the neurons. Also, NPL 2 discloses a neurochip wherein a plurality of roughly circular enclosures known as “cages” (approximately 9 μm height) such as shown in FIG. 3, are formed on a plate, neurons are situated in the space at the center section of each cage, and the axons of neurons are caused to elongate toward neurons in adjacent cages, through several tunnels provided in the cage.